By Brian M. Rosenthal
Seattle Times staff reporter

After months of campaigning and countless hours of television advertising, Washington state is finally ready for the climactic conclusion of Election 2012.

But with one of the country's most competitive governor's races, other close matchups and a pair of potentially historic too-close-to-predict ballot measures, state officials and political insiders are preparing for a long night — or week — of ballot counting after Tuesday's voting deadline.

More than 1.5 million ballots have been returned, and hundreds of election staffers are working to process them, but another 1.5 million or more are expected in the run-up to the deadline. That flood, officials say, will be impossible to tabulate on election night because the state's all-mail-in system requires ballot processing that takes at least a day.

Unlike in Oregon, which requires all mail ballots to be received by 8 p.m. on Election Day, and thus can report most results that night, ballots here need only be postmarked by the deadline. That means some ballots from around the country and overseas will arrive days and weeks after Tuesday.

Campaign staffers from both major political parties say they're not counting on everything getting decided Tuesday, especially in the governor's race and the nationally watched gay-marriage and marijuana-legalization initiatives.

Both Republicans and Democrats will have several attorneys on retainer in case of a situation like 2004, when Democratic gubernatorial candidate Chris Gregoire beat Republican Dino Rossi by 133 votes after two recounts and a court challenge. The case wasn't settled until early June.

"We're ready for anything," said Kirby Wilbur, chairman of the Washington State Republican Party.

Overall, Secretary of State Sam Reed predicts that 81 percent of the state's 3.9 million registered voters will cast ballots this year, less than the 2008 record of 84.6 percent.

In King County, election officials are predicting 87 percent turnout among 1.2 million voters and say the number of ballots returned so far indicates it could go even higher.

But only about 60 percent of votes will be reported on Election Day, officials said. By the end of the week, closer to 90 percent of votes will be tabulated.

"Every ballot has to be signature verified, inspected, scanned and resolved," said Kathy Fisher, election manager in Yakima County, which was already at 41 percent participation as of Friday. "It's a lengthy, labor-intensive process."

That process started as soon as voting began in mid-October.

King County Elections, which has 75 full-time staffers, hired another 500 temporarily for the count, said spokeswoman Barbara Ramey. That agency has received more than half a million ballots, far above forecasts, she said.

Spread throughout the agency's sprawling Renton headquarters, wearing bright-blue gloves and bright-green lanyards, the workers Friday sorted the ballots and compared the signature on each envelope to one on file. Between 2 and 3 percent don't match, and in those cases, the workers will call each voter to try to resolve the issue.

After the signature is verified, workers open the envelopes and make sure the ballots don't have problems like stray marks that make it impossible for the counting machines to read them. In some cases, the ballot will have to be manually duplicated before processing.

Once ready, ballots are scanned and the images are transferred to a large computer locked in a room only a handful of people can access. Under state law, the actual tabulation of votes can't begin until after 8 p.m. Tuesday.

On election night, results will spill out between 8 and 9 p.m. Most counties will release their entire vote total for the night in one batch; in King County, it's scheduled for 8:15. Pierce County, however, is planning a second dump at 11 p.m.

The Secretary of State's Office will compile the results and post them on its website.

The counties will update their totals each weekday thereafter, until Nov. 27 deadline. The final results will be certified Dec. 6, one month after Election Day.

The election-night percentages likely will look different from the final result; in 2010, Democratic U.S. Sen. Patty Murray was leading Republican challenger Rossi 50.5 to 49.5 percent after the initial tally, but went on to win 52.4 to 47.6 percent.

The all-mail system increases voter turnout and reduces state costs, said Dave Ammons, spokesman for the secretary of state. But the slow process irks many, including Secretary Reed.

The state has resisted moving to an Election Day ballot receipt deadline, like Oregon's, out of fear that it will result in some votes being disqualified.

Those who support a change point out that Oregon's voter turnout is consistently a point or two higher than Washington's.

"Plus," Ammons grumbled, "they'll probably know who won the election on Election Day."